How to fill exterior cavity around sash window frame?


27 Nov 2007
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United Kingdom

The pointing around one of my sash window frames was cracked into several pieces and moving around in the joint allowing ingress of mositure so I raked it all out in readiness to renew.

The pointing was very thin and was no longer attached on the brickwork side. It was only held in place at all by the bead of sealant to the window frame side. There was nothing at all behind the pointing - just a large void (see pic) which I was not expecting. A simple job has turned into something a bit more challenging hence my post. View pic of the cavity:

I would really appreciate your recommendations on what to do about this cavity before I repoint the front and reseal around the frame, especially which material to use to pack the hole. I've given the brickwork and frame inside the void a good brushout and clean, ensuring that all loose material was removed. The woodwork is in good condition.

Thank you.
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One idea is to back fill the cavity with expanding foam (wet the area first) but I think I'd be rolling up some wire mesh into a tube, pushing it into the gap and then pointing to that - with a couple of coats.
The mesh allows the mortar to key, and will also make it much stronger. Use a fairly stiff mortar mix.
John :)
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put some lime in the mix and wet it in first,point it up to about 8mm thick with a rough edge over the bricks,leave that to go off a bit lay a piece 2x1 over the pointing run down the edge with a pointing trowel knock off the rough edges hey presto lovely bit of neat pointing

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